Aleš Lombergar

From http://www.myinsulators.com/glass-factor…

Hope this helps!

Diamond logo (no letters or numbers inside)……..Uncertain, possibly Diamond Glass Co, Montreal, Quebec (1891-1913), or Diamond Glass Company, Royersford, PA (1885-1990). (Diamond Glass Company of Royersford was purchased in 1985 to become part of Diamond-Bathurst, and in 1987 the factory was then acquired by Anchor Glass Container Corporation, who closed down the plant in 1990). Some bottles may well be products of the Illinois Glass Company, Alton, IL., which definitely used a diamond mark with numbers and/or letters within it on many types of bottles.
Diamond with an “I” inside…………See “I within a Diamond” mark.
Diamond with letter & number or letter & numbers combination within it………Illinois Glass Company, Alton, IL, definitely produced at least some of these.
Diamond with 2-, 3- or 4-digit number inside………Illinois Glass Company, Alton, IL (1873-1929). (Numbers found within a diamond on several types of bottles have been matched with catalog numbers found in Il Glass Co. bottle catalogs.) Exact period when this mark was used is uncertain. Other companies that might have produced some of the bottles found with these basemarks include Diamond/Dominion Glass Company, Montreal, Quebec, Canada & other locations; and the Diamond Glass Company, Royersford, PA (1885-1990)

Diamond superimposed over an oval [letter O] and an I…………..Owens-Illinois Glass Company, Toledo, OH (head office) and other plant locations (1929-to date). Two examples of the mark are shown here. This mark was used from 1929 (possibly not actually engraved on molds until early 1930) up to c.1957. As there was a gradual changeover to the ‘new’ trademark (with the diamond removed) which occurred over a period of four or five years (beginning in 1954), some bottle molds already in use were not re-engraved until as late as 1957 or 1958. (I have a soda bottle dated 1959 with this “old” mark!). However, after 1958 the great majority of O-I bottles carried the “new” trademark, which was simply an I inside an oval. (See “I inside an O” mark). On very small bottles, the mark may be indistinct and the “I” may be invisible, or just a tiny dot. On the typical bottle, there is usually a number to the left of, to the right of, and below, the trademark. (Note: This arrangement is the most commonly seen, but some bottles, such as liquor flasks, are marked in other ways and so are found with a different code configuration.) The number on the LEFT of the diamond logo is the plant code number, the number on the RIGHT is a date code, and the number below the logo indicates the mold cavity or serial number. Examples: plant code #2 stood for the Huntington, WV plant; “3” was the Fairmont, WV plant; “7” indicated Alton, IL; “9”, the Streator, IL factory; “12” was Gas City, IN; “14” was the Bridgeton, NJ plant, etc. Some of the numbers have been re-used for other plants opened in later years, however. For a page with more plant code numbers, courtesy of Dick Cole (fruitjar.org), click here .
Known as Owens-Illinois, Inc. since 1965, this corporation is currently (2005) the largest manufacturer of glass containers in the western hemisphere, with plants located worldwide. Owens-Illinois has continued to diversify in recent years into other types of industries, including plastic and metal packaging. Click here for O-I’s website.